How Selenium affects Animal Health

Horses react more strongly to an excessive selenium exposure than cows or pigs. Intoxication causes are usually selenium-rich feed or water (more common in the USA or Canada then in Europe).

Symptoms of a chronic exposure and intoxication, referred to as 'alkali disease', are loss of long hair, hoof changes and a generally fatigued appearance. Symptoms of a subacute intoxication, called 'blind stagger', are ataxia and vision problems. The acute form of intoxication is the selenosis, which can cause cardiac insufficiency and sudden death.

Other symptoms of a selenium overexposure are weight loss, colic or diarrhea, problems swallowing, garlic-smelling breath, walking problems with a typical stiff gait.

Fur analysis can detect chronic overexposure. Blood testing reveals if the overexposure is immediate.

According to the National Research Council (NRC), the recommended daily dose of selenium for dogs is 0.5 µg per kilogram of body weight. The maximum tolerable dose of selenium for dogs is 0.9 µg per kilogram of body weight according to the NRC. However, these values ​​are only guidelines and can vary depending on individual factors such as the dog's age, health status, activity and diet. Athletic dogs or those exposed to high environmental stress may have a higher need. It should also be noted that the bioavailability and toxicity of selenium depend on the chemical compound.

Experts distinguish between different compounds and their individual bioavailability. As a reminder: bioavailability determines how well an organism can absorb a nutrient. Organic selenium is better tolerated and safer than inorganic selenium.

• Inorganic selenium, also referred to as selenite and selenate is quickly absorbed and is therefore considered more toxix.
• Selenomethionine and selenocysteine ​​are organic selenium compounds. They are less quickly available and therefore of low toxicity.

Selenium is needed for important body functions such as the formation of the enzyme glutathione peroxidase, which neutralizes free radicals and protects cells from oxidative stress. This in turn protects against inflammation, premature aging and diseases such as cancer or arthritis. Selenium also regulates thyroid hormones, which affect the dog's metabolism, growth and development. The quality of sperm and the health of the ovaries are supported by this trace element.

During a high selenium exposure, the typical garlic-like smell or that of rotten radish occurs, which is caused by the formation of dimethylselenide. A selenium blood test is necessary for the diagnosis of selenium poisoning as part of the veterinary examination.

The fur analysis is useful if a long-term overdose from feed or supplements is suspected.